Counter system for step-and-repeat drafting arm

ABSTRACT

An instant-read counter system in combination with a step and repeat drafting head mechanism of the type having the steps defined by axially spaced reference surfaces adjusted by an elongate rotating anvil member mounted on screwthreads, the counter proper being a mechanical numerical counter driven by an attached pinion through a gear on a shaft coaxial with the rotating anvil member and engaging a slot in the tubular end of it; a simplified thrust arrangement on the shaft and special adjustment mechanisms for the rotating anvil member and the pinion and gear relation are also disclosed. The counter being operable to count and indicate the valve of the steps.

' United States Patent Raffensparger COUNTER SYSTEM FOR STEP-AND-REPEAT DRAFTING ARM Primary Examiner-Richard E. Aegerter Assistant ExaminerCharles E. Phillips Attorney, Agent, or Firm-John F. McClellan, Sr.

[57] ABSTRACT An instant-read counter system in combination with a step and repeat drafting head mechanism of the type having the steps defined by axially spaced reference surfaces adjusted by an elongate rotating anvil member mounted on screwthreads, the counter proper being a mechanical numerical counter driven by an attached pinion through a gear on a shaft coaxial with the rotating anvil member and engaging a slot in the tubular end of it; a simplified thrust arrangement on the shaft and special adjustment mechanisms for the rotating anvil member and the pinion and gear relation are also disclosed. The counter being operable to count and indicate the valve of the steps.

5 Claims, 7 Drawing Figures US. Patent Dec. 16,1975 Sheet 1 of2 3,925,900

FIGS

FIG 4 FIG U.S. Patent Dec. 16, 1975 Sheet20f2 3,925,900-

COUNTER SYSTEM FOR STEP-AND-REPEAT DRAFTING ARM This invention relates generally to measuring devices and particularly to adjustable drafting arms.

Principal objects of the invention are to provide a self contained instant-read system in combination with a step-and-repeat drafting head of the type in which the desired step increments are set by manual rotation of a knob, to replace the usual vemier arrangement, to provide a simplified easilymanufactured, easily adjusted, reliable and economical mechanical numerical counter drive for the purpose, and to provide an adjustment having these same advantages for calibration of the knob rotation with respect to the spacing of the reference surfaces determining the step increments.

Numerical counters of both the mechanical and the electrical type are known in the prior art of drafting arrangements, examples being US. Pat. No. 3,719,997 issued Mar. 13, 1973, to C. K. Hulen, US. Pat. No. 2,239,323, issued Apr. 22, 1941 to I. W. Hicks and German Pat. No. 223,579 issued on Nov. 27, 1909.

However, these old-art devices are not self-contained in the sense of the present invention, and disclose arrangements not adapted to provide the above set out advantages of this invention.

In brief summary, given for cursive description only, the invention includes a slot co-axial-coupling of a knob rotated screw thread mounted anvil with a me chanical counter through a specially mounted shaft, with adjustment structure.

The above and other objects and advantages of the invention will become more readily apparent on examination of the drawings, in which, like reference numerals denoting like parts:

FIG. 1 is an isometric view of the invention in use in a drafting system;

FIG. 2 is a top plan view of the step-and-repeat mechanism of FIG. 1;

FIG. 3 is an end elevation;

FIG. 4 is a side elevation;

FIG. 5 is an end elevation;

FIG. 6 is a bottom isometric view, and

FIG. 7 is a bottom plan detail, partly in section.

Referring now to the Figures in detail, FIG. 1 shows generally a drafting table I having along one side thereof a step and repeat mechanism 10 guided by a rail 14 having a rod 16 passing there-through and engaged by the mechanism.

The mechanism 10 rigidly mounts to it a drafting arm A by means of screws or the like or the arms may be pivoted to the mechanism by any of the well known means for the purpose.

Paired rod-release grips 18a, 18b. for sliding the mechanism freely along the rod and paired incremental-advance grips 20a, 2017 are provided on the top surface of the mechanism. Incremental-advance setting knob or step-setting knob 22 establishes the distance which squeezing together the pair of incrementaladvance grips will draw the mechanism 10 along the rod, and hence also the rail. A mechanical numerical counter 24 facing upward in the top of the mechanism has responsive connection to the setting knob 22 so that incremental-advance step settings established by the knob are instantly and accurately readable, without need for computation, matching, or other interpolation.

2 FIGS. 2-5 detail the various aspects of the FIG. 1 incremental-advance mechanism in plan, side and end views.

FIGS. 6 and 7 illustrate the arrangement and interaction of the parts of the improved step and repeat drafting head mechanism of this invention, in bottom views.

Frame 26 is an elongate box shape open at the bottom, and guides on the rail 14 by means of squarenotched end plates 28, 30 which fit the rail. The end plates 28, 30 preferably are of anti-friction plastic such as polypropylene and the remainder of the mechanism is metal.

Rod 16 passes through sliding-fit holes 32 in the end plates 28, 30 spaced equidistant from the respective notches 34 in the end plates.

Three rod-clutches control position of the mechanism 10 with respect to the rod 16. The first two clutches are the rod-engaging perforate lower ends 18c, 18d of paired release grips 18a, 18b referred to above, pivot in opposite directions at the slots 36, 38 in the frame through which they pass and are urged together by suitable springs 40, 42 bearing on the frame, cramping and locking the rod 16 where it passes through them, each preventing rod travel in .the direction in which spring-urged. The third rod-clutch is a similar but lateral lower extension 20c of incremental advance grip 20a pivoted by a pin 44 to sliding block 46. The rod 16 passes through hole 48 in this third grip and is urged from left to right in the view by it when the rod is released from detention in that direction by clutch of the first pair 18c, 18d Squeezing the incrementaladvance grips 20a, 20b, together along slots 50, 52 accomplishes both the required release, by means of release pressure on clutch 180 through bent member 54 which engages a hole 56 in the grip, and the advance.

Springs 58 and 60 respectively restore the pivotal position of the third or incremental-advance grip 20c and the sliding block 46.

Extent of incremental advance is determined by the distance to which angular extension 62 of the sliding block 46 is limited in travel by a first reference surface 64 on the end of fixed tubular anvil 66 and a second reference surface 68, which consists of an annular radial surface on the inner end of radial protrusion 70 on the end of screw-thread monted movable anvil assembly 72.

A screw fixes the tubular anvil 66 to frame member 76. A peripheral thread 78 having a considerable longitudinal extent along one end of the fixed anvil engages a corresponding interior thread 80 in the knob 22, serving to mount the knob and the elongate shank 82 screwed to the knob, rotatably. Locking screw 84 in the threaded bore 86 of the knob 22 bears on the threaded end of the shank 82 and holds the adjustment set between knob and shank.

The opposite end of the elongate shank 82 axially extends beyond the interior reference surface previously noted in a tublar shape 88 having a pair of diametrically opposed radial slots 90 extending along it to the end, which is open.

Shaft 92 has one end 94 coaxially within the split tubular end of the shank 82 and a fixed diametral pin 96 engaging the slots. Journal 98 screwed to the frame supports shaft 92. Gear 100 is pinned or otherwise fixed to the shaft proximate the other end and has a thrust-washer 102 between it and the journal.

Pinion 104 on the input shaft of numerical mechanical counter 106 engages the gear, and the other end 3 108 of the shaft rests against a face 110 of the housing of the numerical mechanical counter, together with the thrust washer 102 between the journal and gear defining the thrust-position of the shaft.

Bracket 112 screwed across the bottom of the frame in position to hold the pinion 104 lateral to the gear 100 has four housing securance slots 114 running parallel with the plane of the gear, permitting the pinion to be adjusted laterally to engage the gear properly.

This arrangement prevents overconstraint of the shaft and gearing while assuring accuracy through precise meshing. Operation of the device is as follows:

CONTROL FOR FREE SLIDING Squeezing together the paired rod-release grips 18a, 18b (FIGS. 1, 2, 4, 6. 7) pivots them to a more parallel position, releasing the cramping-type grip of the lower ends 18c, 18d of these members on the rod 16 in exactly the same manner as transom-control rods in buildings are gripped and released. In this mode the entire device, straightedge and all (A, FIG. 1) can be slid freely along the rod 16 and the guiding rail 14 (which serves only as a guide and is never clamped). Springs 40, 42 restore the clamping when the operator releases his squeeze on these grips. Paired grips are used for the same reason as on a transom-control rod, the cramping-type clamping of either grip is effective in only one direction; to prevent sliding in both directions, oppositely inclined grips are provided.

CONTROL OF INCREMENTAL ADVANCE When it is desired to draw a series of parallel horizontal lines, equally spaced apart, or to do some similar operation, squeezing together the incremental-advance grips 20a, 20b (FIGS. 1, 2, 4, 6) between the drawing of the successive lines provides the necessary spacing by parallel-advancing the straight edge (A, FIG. 1) a distance predetermined by the setting of knob 22. Rotatively setting knob 22 (FIGS. 6 and 7) sets a desired limit on the freedom of travel of the integral angular extension 62 of sliding block 46 (FIG. 6) which slides on rod 16.

The desired limit of travel is established by the spacing between reference surface 64 on the fixed tubular anvil 66, and the corresponding reference surface 68 which is integral with the knob. Sliding block extension 62 is free to travel only the distance between these two elements, thus limiting the travel of the sliding block 46 along the rod 16.

The force urging the mechanism 10 to travel along the rod is applied as follows: motion of grip a pivots lateral lower extension 200 about pin 44 of the sliding block 46, and thus grips rod 16. Simultaneously, motion of grip 20b advances rod 54 which in turn pivots grip 18a, 18c and releases it. Continued squeezing together of grips 20a and 20b then slides the balance of the mechanism, which moves with grip 20b, towards grip 20a and lateral lower extension 200 which are anchored or clamped to rod 16 as described. Release of the squeezing pressure permits spring 58 to release the grip of 20c on the rod, and spring 60 to release pressure on grip 18a, 18c, permitting spring 40 to restore the clamping of grip 18a, 18c on the rod 16.

In the process of setting the incremental advance, relative axial .motion between the setting knob assembly and the drive shaft 92 is accommodated, as noted by the slot 90 and pin 96 relation.

With 20 threads per inch screw-threads mounting the moving anvil 72, a gear-to-pinion ratio of five to one gives a three-place decimal-inch readout which taken by and large gives vernier accuracy but several times faster. With the arrangement described still greater gear ratios can be used to obtain readings of finer divisions of settings.

The knob adjustment described permits angular indicia to be marked on the knob 22 also calibrated accurately in conjunction with the numerical mechanical counter 106to spin in increments of full turns (fifty thousandths in the example) or other multiples or fractions.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed and desired to be protected by United States Letters Patent is:

1. In an adjustable step and repeat drafting arm mechanism having: a frame (26), a tubular anvil (66) on the frame, with a peripheral screwthread (78) extending longitudinally along a portion thereof and terminating at a first end thereof and a first reference face (64) on the second end thereof, an elongate movable anvil (72) with an interior screwthread (80) adjacent a first end thereof engaging said peripheral screwthread (78); a knob portion (22) at the second end of said movable anvil, an elongate shank (82) extending axially through and projecting beyond the tubular anvil (66) with a first end of said shank connected to said movable anvil; the second end of said shank having a radial protrusion (70) with an annular radial surface (68) on the inner end of said radial protrusion, said annular radial surface being a second reference face, a sliding block (46) disposed between said'first and second reference faces with the elongate shank (82) passing through a hole in the sliding block (46), a rod (16) passing through the frame (26), means (200) having pivotal attachment to the sliding block (46) for grasping the rod (16) and advancing the frame therealong in adjustable increments, and means for indicating said increments, the improvment comprising:

the means indicating including: said radial protrusion having tubular shape (88) and having at least one slot (90) extending therealong, a shaft (92) coaxially aligned with the tubular shape (88), means for engaging a first end of the shaft (92) with said slot (90) such that rotation of said radial protrusion will cause rotation of said shaft, a journal (98) rotatably mounting the shaft to said frame, a gear (100) fixed proximate the second end of the shaft, a numerical (106) counter having an input shaft, a pinion (104) on the numerical counter input shaft, and means for adjustably holding the numerical counter (106) in a position engaging the pinion (104) with the gear (100), such that rotation of said knob will adjust the distance between said first and second reference faces and will concurrently rotate said counter input shaft to give a value for said spacing.

2. In a mechanism as recited in claim 1, said at least one slot (90) being longer than the longitudinal extent of said peripheral screw thread (78).

3. In a mechanism as recited in claim 2, said journal (98) positioned between the first end of the shaft and the gear (100), a thrust washer (102) between the journal and the gear providing thrust retention of the shaft in a first direction, and the second end (108) of the shaft axially resting against the numerical counter (106), providing thrust retention of the shaft in a second direction.

4. In a mechanism as recited in claim 3, the means for adjustably holding the numerical counter (106) in a position engaging the pinion (104) with the gear (100) comprising a bracket (112) attached to the frame (26) and having plural slots (114) parallel with the plane of the gear (100), the bracket proportioned for holding the numerical counter (106) lateral to the gear (100), 

1. In an adjustable step and repeat drafting arm mechanism having: a frame (26), a tubular anvil (66) on the frame, with a peripheral screwthread (78) extending longitudinally along a portion thereof and terminating at a first end thereof and a first reference face (64) on the second end thereof, an elongate movable anvil (72) with an interior screwthread (80) adjacent a first end thereof engaging said peripheral screwthread (78); a knob portion (22) at the second end of said movable anvil, an elongate shank (82) extending axially through and projecting beyond the tubular anvil (66) with a first end of said shank connected to said movable anvil; the second end of said shank having a radial protrusion (70) with an annular radial surface (68) on the inner end of said radial protrusion, said annular radial surface being a second reference face, a sliding block (46) disposed between said first and second reference faces with the elongate shank (82) passing through a hole in the sliding block (46), a rod (16) passing through the frame (26), means (20c) having pivotal attachment to the sliding block (46) for grasping the rod (16) and advancing the frame therealong in adjustable increments, and means for indicating said increments, the improvment comprising: the means indicating including: said radial protrusion having tubular shape (88) and having at least one slot (90) extending therealong, a shaft (92) coaxially aligned with the tubular shape (88), means for engaging a first end of the shaft (92) with said slot (90) such that rotation of said radial protrusion will cause rotation of said shaft, a journal (98) rotatably mounting the shaft to said frame, a gear (100) fixed proximate the second end of the shaft, a numerical (106) counter having an input shaft, a pinion (104) on the numerical counter input shaft, and means for adjustably holding the numerical counter (106) in a position engaging the pinion (104) with the gear (100), such that rotation of said knob will adjust the distance between said first and second reference faces and will concurrently rotate said counter input shaft to give a value for said spacing.
 2. In a mechanism as recited in claim 1, said at least one slot (90) being longer than the longitudinal extent of said peripheral screw thread (78).
 3. In a mechanism as recited in claim 2, said journal (98) positioned between the first end of the shaft and the gear (100), a thrust washer (102) between the journal and the gear providing thrust retention of the shaft in a first direction, and the second end (108) of the shaft axially resting against the numerical counter (106), providing thrust retention of the shaft in a second direction.
 4. In a mechanism as recited in claim 3, the means for adjustably holding the numerical counter (106) in a position engaging the pinion (104) with the gear (100) comprising a bracket (112) attached to the frame (26) and having plural slots (114) parallel with the plane of the gear (100), the bracket proportioned for holding the numerical counter (106) lateral to the gear (100), and means for adjustably holding the numerical counter in the slots.
 5. In a mechanism as recited in claim 1, means for adjusting the extent of engagment of said interior screwthread (80) and said peripheral screwthread 78 relative to the spacing between said first and second reference faces, comprising a threaded end on the elongate shank (82) engaging a tapped hole (86) in the knob portion (22), and a locking screw (84) in the tapped hole pressing axially against the elongate shank (82). 